Load cell having a thin film strain-inducible element

Abstract

A load cell wherein strain gauges are produced by a thin film process on a pattern forming surface of a strain-inducible element in such a manner that the resistances of the strain gauges are varied in accordance with deformations caused in thin portions of the strain-inducible element, and adjustable resistors are deposited by the thin film process for an electric circuit assembly including a differential amplifier, a potential divider, a signal amplifier and a zero-point setter. And each of the resistors is adjusted by trimming simultaneously with trimming adjustment of the strain gauges.

What is claimed is: 
     
       1. A load cell comprising: a strain-inducible element having four thin portions deformable in the shape of a parallogram and having a pattern forming surface;   A plurality of thin film deposited strain gauges formed on said pattern forming surface wherein each of said gauges is positioned in correspondence with said thin portions and wherein said strain gauges are interconnected to constitute a bridge network;   differential amplifier means including a thin film differential amplifier resistance means;   power supply means;   potential divider means whose input is connected to the output of said power supply means and wherein said potential divider means includes a potential divider resistor means wherein the output of said divider means is connected to the input of said differential amplifier means;   signal amplifier means including a thin film gain determining resistor means wherein one output of said bridge network is connected to one input of said signal amplifier means;   zero-point setting means including a thin film setting resistor means wherein said setting means is connected to the output of said differential amplifier means and to one output of said bridge network;   wherein each of said differential amplifier means, said potential divider means, said signal amplifier means and said zero-point setting means is deposited on said pattern forming surface together with said strain gauges in such a manner so that at least one of said differential amplifier resistor means, said divider resistor means, said gain determining resistor means and said setting resistor means is adjustable by trimming simultaneously with trimming adjustment of said strain gauges.   
     
     
       2. The load cell according to claim 1 wherein said differential amplifier resistor means is adjusted by trimming simultaneously with trimming adjustment of said strain gauges. 
     
     
       3. The load cell according to claim 1 wherein said divider resistor means includes a plurality of resistors which are adjusted by trimming simultaneously with trimming adjustment of said strain gauges. 
     
     
       4. The load cell according to claim 1 wherein said gain determining resistor means includes at least one resistor which is adjusted by trimming simultaneously with trimming adjustment of said strain gauges. 
     
     
       5. The load cell according to claim 1 wherein said setting resistor means includes a resistor which is adjusted by trimming simultaneously with trimming adjustment of said strain gauges. 
     
     
       6. The load cell according to claim 1 wherein said differential amplifier resistor means, said divider resistor means, said gain determining resistor means, and said setting resistor means are all adjusted by trimming simultaneously with trimming adjustment of said strain gauges.